End-stage kidney failure: your experience with lab values vs behavior?

[whatwouldjanetdo]

Hi, my 14 y/o dog was diagnosed with kidney failure about a month ago. Even with sub-q fluids administered every other day and eating a kidney diet, it's progressing quickly. She's now fallen into "end-stage" according to her creatinine values, but she doesn't behave like she's feeling worse. She looks great, still has an age-appropriate amount of energy to chase rabbits, play, and doesn't act like she's in pain. So I'm very confused.

I've been searching to find information about the upper limits of end-stage lab values to grasp how much of a range we're working with, but I can't find anything. Like others with dogs suffering from kidney failure, not knowing is really difficult and I'd like to formulate an idea of how much time we have left. Because right now, the labs and her behavior are telling me two very different stories.

Her creatinine levels were as follows:
5/24 2.9
6/5   3.4
6/14 3.9
6/26 5.1

BUN has also steadily increased over the same period.

I've seen other members post creatinine values as high as 13 in other threads, but I don't know if that is unique or not? How high did your dog's creatinine get? Did the lab values help you make a decision about how to proceed with your dog's care or euthenasia? My vet has said there's no point in continuing to test her levels, and that we should be "counting time in weeks, not months." Again, this is really hard to get my mind around because she in no way behaves like a dog in her final weeks of life.

I'd greatly appreciate input from anyone with a similar experience. Thank you.